Colonic membranes will be isolated from hog and rat colon by zonal density gradients and free flow electrophoresis. The membrane will be analyzed enzymically, morphologically and for protein, CHO and lipid composition. These techniques will then be applied to the induced rat colonic tumor. Using covalent labelling techniques membrane topology of the colon will be studied. BIBLIOGRAPHIC REFERENCES: Characterization of gastric mucosal membranes. VIII. The localization of peptides by iodination and phosphorylation. J. Biol. Chem. 250, 4802-4809, 1975. Saccomani, G., Shah, G., Spenney, J.G., Sachs, G. Quantitation of conductance pathways in antral gastric mucosa. Spenney, J.G., Flemstrom, G., Shoemaker, R.L., Sachs, G.: J. Gen. Physiol. 65, 645-662, 1975.